While it is not known to evolve into or from any Pokémon, it does seem to be related to Minun.

Biology

Plusle is cream-colored bipedal Pokémon with red markings. It has a dot-like nose, and a cream-colored plus sign in the middle of its circular red cheeks. It has long, flat ears that are mostly red. Its limbs are stubby and digitless, and it has red front paws. Its short tail is tipped with a red plus sign.

Plusle can create sparkly pom-poms by shorting out the electrical current in its palms. It uses these pom-poms to cheer on its teammates, and will cry loudly if they lose. It climbs telephone poles to absorb electricity. It lives in grassy areas.

In the TCG

Other appearances

Excess data found on the game disc includes data for seven playable characters cut from the final roster, including Plusle and Minun as a tag team akin to the Ice Climbers. However, in the final version of the game, Plusle just appears as a random trophy alongside Minun.

Trophy Information

It appears with its counterpart, Minun.

"Cheering Pokémon. Plusle and Minun produce positive and negative energy, respectively. They both love cheering on their partners and place the encouragement of their partners over their own safety. To cheer, they short their electric currents to produce sparks that grow in intensity as their partners get into trouble."